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Mailing list for the LaTeX3 project <[log in to unmask]>
Tue, 7 Sep 2021 17:22:37 +0100
Mailing list for the LaTeX3 project <[log in to unmask]>
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Jonathan Fine <[log in to unmask]>
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Summary: TeX converts source to DVI, an abstract page description language.
By definition, a rich DVI file contains word-by-word backlinks to the TeX
source. We discuss how to create rich DVI, and how to render it to an
accessible PDF. We compare this to the LaTeX Project approach.

Date and time: Thursday 9 September, 6.30 to 7.30pm UK time.
UK time now:
Zoom URL:

Producing accessible PDF from LaTeX source would be a tremendous advance
(as would reliable production of accessible HTML). A large part of the
problem of creating accessible PDFs is to merge two document trees, namely
the TeX source (as HTML) and the PDF.  At last month's TeX Conference Frank
Mittlebach presented his solution to this problem.

At tomorrow's TeX Hour I'll present my solution, via the concept of rich
DVI files. This goes back 25 years, to my TUGBoat article "Editing .dvi
Files, or Visual TEX". Although in some ways dated, the basic concepts are
still sound and even more relevant than before.

My approach is to pre-process the source tree so that every word (and
similar source objects) is tagged in the resulting DVI file. This will then
give a rich DVI, from which an external program can create an accessible
PDF. Frank's approach is similar, except that he uses complex and ingenious
LaTeX macros for everything, and tags only the paragraphs.

Frank's approach leads to a multi-year journey to modernize LaTeX, and
avoids the need for a post-processor. My approach can use current LaTeX, by
use of an input filter to add tagging, and an output filter to render the
rich DVI to accessible PDF.

This is an important choice, which will affect TeX for over 30 years. If
you're keen, you can read about these two approaches at

You're invited to tomorrow's TeX Hour: Rich DVI files and accessible PDF.
Date and time: Thursday 9 September, 6.30 to 7.30pm UK time.
UK time now:
Zoom URL:
Meeting ID: 785 5125 5396
Passcode: knuth

Last week's TeX Hour was on Docs and help for LaTeX users.  The videos are
available at

Arising from that is a project to help users find existing advice on LaTeX
best practice,

Happy TeXing